mrdoob/timer.js — comment on commit 098198480dd9c27bffec236bb523feba1a9c272d
File: src/Timer.js line 24
By alteredq:

Wouldn't this potentially cause spurious values if reading of `currentDelta` happens at this precise moment (before `currentDelta` being set again on the line 40)?

So in long run you could occasionally get some negative deltas and get some really weird behaviors.